How did the Greeks learn to write from the Phoenician alphabet without prior knowledge of reading and writing? Was there an oral tradition of writing in ancient Greece?

Yes there was. It is called Linear. There are 2 Linears. The Linear B, a written system of Greek 3.300 years old which has been deciphered. Actually my name ΔΗΜΗΤΡΗΣ/Demetres appears at Linear B. (Below a Photograph of my name in Linear B). Yeap I have one of the most ancient names globally.

And Linear A, -which is an Hierglyphic Language (Probably), and still we haven’t managed to figure out the correspondence between Hieroglyphics and Sounds. Second Photograph.